In a typical wireless communication system, only one carrier is considered even if a bandwidth between an uplink and a downlink is configured differently from each other. The carrier is defined with a center frequency and a bandwidth. A multi-carrier system uses a plurality of component carriers (CCs) having a smaller bandwidth than a full bandwidth.
The multi-carrier system can support backward compatibility with respect to legacy systems, and significantly increases a data rate by using multiple carriers.
Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a most dominant next mobile communication standard. The 3GPP LTE system supports only one bandwidth (i.e., one CC) among {1.4, 3, 5, 10, 15, 20}MHz. However, an LTE-advanced (LTE-A) system which is an evolution of the 3GPP LTE employs multiple carriers.
Even if the multi-carrier system uses a plurality of CCs, it may be ineffective for a base station (BS) and a user equipment (UE) to use all CCs concurrently. Therefore, dynamic scheduling for the CC is required. For example, more CCs are allocated to a UE that requires a high data rate, and less CCs are allocated to a UE that requires a low data rate such as voice.
It is necessary to ensure transmission reliability in a control signal such as activation of the CC. This is because when mutually activated CCs become different between the BS station and the UE, data loss may occur and service quality may deteriorate significantly.
Accordingly, there is a need for a method capable of reliably activating a plurality of CCs in a multi-carrier system.